get username online in asp.net to database

i need help about asp.net. i'm making application with login form from visual studio and using loginname in every pages, my questions is:
how to get username online into database when user insert/update? because i wont to know 'who create this data'

Create Session variable or Hidden control and assign username into session vairable or hidden control when the login is succssfull. Using session variable u can know who is inserting the data or updating

Once the login is successful u can came to know the username as 'Create by', that assign into session or cookie variable. When user is try to insert/update the record, pass this username into backend to update 'Create by' using the Insert/update query.